1. Field of the Invention
The invention relates to a control device and control method for a vehicle.
2. Description of Related Art
In recent vehicles, a control device that assists the driver in driving operation during running of the vehicle has been developed in order to improve ease of driving during running of the vehicle, reduce a burden on driver's driving operation and further improve safety during running of the vehicle.
For example, in a rear-end collision prevention system described in Japanese Patent Application Publication No. 2005-132338 (JP-A-2005-132338), wireless communication is allowed between vehicles, a preceding vehicle transmits a predicted sudden braking situation through wireless communication, and a host vehicle that has received information from the preceding vehicle keeps a brake system in a brake actuation standby state. By so doing, when the driver of the host vehicle performs braking operation, the host vehicle immediately starts braking, so it is possible to prevent the host vehicle from hitting the rear end of the preceding vehicle even when the preceding vehicle brakes suddenly.
However, when running information is exchanged between vehicles through wireless communication, the running information of another vehicle may not be appropriately acquired depending on a communication condition. Therefore, when vehicle running control is executed on the precondition that running information is exchanged between vehicles through wireless communication, it may be difficult to appropriately execute running control when it becomes impossible to appropriately acquire the running information of another vehicle. For example, when an inter-vehicle time between the host vehicle and the preceding vehicle (that is, a time that elapses until the front end of the host vehicle reaches the same position as the current position of the rear end of the preceding vehicle) is set and then the host vehicle runs while acquiring the running information of the preceding vehicle through inter-vehicle communication with the preceding vehicle, it becomes difficult to maintain appropriate follow-up running when it becomes difficult to acquire the running information of the preceding vehicle because of a communication breakdown, or the like.